In that sense I suppose this phenomenon is called "understatement."
The same is true of Dennis Ritchie: he’s just a programmer—because the word “programmer” was originally invented to describe people like Ritchie. But by that same historical standard, most modern “programmers” aren’t; they’re just code-monkeys.
The Usain Bolt example is different—Bolt really is an exceptional runner, rather than being a denotationally-central example of what it means to be a runner. When the word “runner” was invented, it referred to the lesser thing, with plenty of central examples; and by that yard-stick, Bolt is more like a “super-runner” or some such. (Similar to how the word “food” developed to refer to a category where the central examples were nutritionally merely-adequate, so now we’ve had to invent the word “superfood” for foods that are, like, really dang good at being food.)
In my experience (working in an academic library and interacting a lot with employees of other academic libraries), most actual present-day academic librarians do not suck at being a librarian. They're not as high-profile as Jessamyn West, but neither are they "computer literate old ladies" -- they use computers constantly in their daily work and are at least aware of issues with digital privacy, copyright law overreaches, etc. I suspect anyone who thinks "computer literate old lady" is still the normative example of a librarian, hasn't interacted with many librarians lately (or perhaps has limited experience e.g. in a small town library).